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Fish datum correction using an XYZ file First put the water depth into SEG-Y header 16 while converting to SEG-Y format. The interpolated floating point water bottom two-way travel time is written into word 50. The interpolated time must be used because the data are high enough frequency that there are several samples per meter. sioseis << eof procs diskin xstar diskoa end diskin format edgetech ipath /data/vol3/henkart//xstar_1999/yr1999day218-0016z.xstar END end xstar binpath xyz.bin ! use a binary version of the XYZ file xyzpath Eureka.xyz ! depth goes in long word 16 deltad 20 end END diskoa opath yr1999day218-0016z.segy end end prout indices l3 l16 r50 fno 0 lno 999999 ftr 0 ltr 9999 end end end eof Now pick the first arrival (the water bottom as seen from the fish). Subtract the picked time from the theoretical time. Use MIX to smooth (average) the shifts from 20 adjacent pings. sioseis << eof procs diskin wbt filter header mix shift gains plot end diskin set 0 .4 fno 99748 lno 8888888 allno no noinc 2 ipath yr1999day218-0016z.segy end end header r59 = r50 - r60 ! subtract the picked time from the theoretical end end mix type 4 hdr 59 weight 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 end end prout indices l3 l16 r50 r59 r60 fno 0 lno 99999 ftr 0 ltr 999 end end shift indices r59 end end filter ftype 0 pass 500 1000 dbdrop 48 end end wbt ! put the picked time in buf(60), normally it goes in 50 index 60 thres .2e-08 track .05 end end gains tgp 0 1 .002 2 .03 4 .06 20 addwb yes end end plot stime .1 nibs 2859 vscale 20 nsecs .2 tlines .01 .05 .1 colors gray opath siofil.gray wiggle 0 anninc 1 ann gmtint trpin 300 def .02 end end end eof sio2sun siofil.gray sunfil xloadimage -r 90 sunfil &